Compressed Air Line Sizing

A receiver won't save compression cost as the pressure and overall volume of air required is the same whether the receiver is there or not.

A receiver will smooth-out the air consumption and may enable a smaller supply pipe to be installed from the cpmpressor. The drawback is that a receiver is a pressure vessel, and periodic insurance assessment of it and burst liability indemnity insurance costings will need to be factored into the installation's economics, as will the shutdown time needed for this to take place.

Dear bhalchandra,

I don't think that you can save compression cost by adding an additional air receiver specific to the client/user requirement. But the additional air receiver will provide some supply of air during compressor outage for a certain period of time depending on the receiver capacity and pressure. Also stable air supply during a sudden surge in user demand.

Compression power is a function of flowrate and head required. Flowrate is fixed by the user demand. The only variable that you can play with is the head required which is depending on the line pressure drop. That means that compression cost is lower for bigger pipe size but investment (compressor + pip[ing & fittings) cost is higher. Therefore, there must be an optimum economic pipe size.

I notice that you are using 2.4m/s as the velocity. The industrial recommended velocity for air is around 30m/s (I believe this is the economic pipe size). However, once you have selected the line size you need to check for the choke flow which is depending on the supply (upstream) pressure and the user (downstream) pressure. Ensure that the choke flow is higher than the maximum demand by client/user.

However, I believe in your case the pressure upstream and downstream already fixed (existing system or compressor already available and user pressure requirement is specified). If this is the case then line sizing is a straight forward calculation.

Dear Mr.Balachandra: this will help you: http://www.engineeringtoolbox.com/compressed-air-pipe-pressure-d_36.html

http://www.transair-usa.com/compressed-air/compressed_air_pipe_sizing.php

http://www.smcpneumaticsdistributor.com/calculators.php

Installing an air receiver will not reduce compression operation and costs, and oversizing the pipe will cost more than the savings on the compressor costs